@article {2848,
	title = {A new 30,000-year chronology for rapidly deposited sediments on the Lomonosov Ridge using bulk radiocarbon dating and probabilistic stratigraphic alignment},
	journal = {Geochronology},
	volume = {2},
	year = {2020},
	month = {Jan-01-2020},
	pages = {81 - 91},
	abstract = {We present a new marine chronostratigraphy from a high-accumulation rate Arctic Ocean core at the intersection of the Lomonosov Ridge and the Siberian margin, spanning the last \~{} 30 kyr. The chronology was derived using a combination of bulk 14C dating and stratigraphic correlation to Greenland ice-core records. This was achieved by applying an appositely developed Markov chain Monte Carlo algorithm for Bayesian probabilistic alignment of proxy records. The algorithm simulates depositionally realistic alignments that are consistent with the available radiocarbon age estimates and allows deriving uncertainty bands associated with the inferred alignment. Current composite chronologies from this region are reasonably consistent with our age model during the Holocene and the later part of deglaciation. However, prior to \~{} 14 kyr BP they yield too old age estimates with offsets that linearly increase up to \~{} 40 kyr near the onset of Marine Isotope Stage (MIS) 2. Our results challenge the robustness of previous regional chronostratigraphies and provide a new stratotype for correlation of sediment cores from this sector of the Lomonosov Ridge and East Siberian slope. In particular, they call for a re-interpretation of events in recent sea-ice proxy reconstructions (Xiao et al., 2015) inaccurately attributed to MIS 3 and the Last Glacial Maximum.},
	doi = {10.5194/gchron-2-81-2020},
	url = {https://gchron.copernicus.org/articles/2/81/2020/},
	author = {Muschitiello, Francesco and O{\textquoteright}Regan, Matt and Martens, Jannik and West, Gabriel and Gustafsson, {\"O}rjan and Jakobsson, Martin}
}
@article {2777,
	title = {Dual-Isotope Constraints on Seasonally Resolved Source Fingerprinting of Black Carbon Aerosols in Sites of the Four Emission Hot Spot Regions of China},
	journal = {Journal of Geophysical Research: Atmospheres},
	volume = {123},
	year = {2018},
	month = {Mar-10-2020},
	pages = {11,735 - 11,747},
	abstract = {Despite much recent efforts, the emission sources of black carbon (BC) aerosols--central input to understanding and predicting environmental and climate impact--remain highly uncertain. Here we present observational δ13C/Δ14C-based constraints on the sources of BC aerosols over the four seasons in each of the four key hot spot emission regions of China: Beijing-Tianjin-Hebei (BTH-Wuqing; where Wuqing is the sampling location), Yangtze River Delta (YRD-Haining), Pearl River Delta (PRD-Zhongshan), and Sichuan Basin (SC-Deyang). Overall, BC loadings were highest in winter, yet elevated loadings were also observed in other seasons, for example, spring at SC-Deyang and fall at PRD-Zhongshan. Annually, the dominant BC sources were coal (50 {\textpm} 20\%) for BTH-Wuqing, liquid fossil for YRD-Haining (46 {\textpm} 8\%) and PRD-Zhongshan (48 {\textpm} 18\%), whereas liquid fossil (42 {\textpm} 17\%) and biomass burning (41 {\textpm} 14\%) equally affected SC-Deyang. There is also different but distinct seasonalities in BC sources for the different sites. As an example, for BTH-Wuqing coal burning increased from summer to winter, while summer and spring BTH-Wuqing were more influenced by liquid fossil. In contrast, for YRD-Haining, the relative importance of emission sources was more constant over the year. These quantitative observational constraints on source-seasonality of BC aerosols in receptor sites located in China{\textquoteright}s four key economic zones highlight that regulatory control on BC aerosol emissions from different fuels should consider both seasonal and regional variations. Our results also suggest that models on estimates of BC-induced climate and air quality should consider variations over both regional and seasonal scales.},
	keywords = {aerosol, BLACK CARBON, carbon isotope, china, emission sources, seasonality},
	doi = {10.1029/2018JD028607},
	url = {http://doi.wiley.com/10.1029/2018JD028607},
	author = {Fang, Wenzheng and Du, Ke and Andersson, August and Xing, Zhenyu and Cho, Chaeyoon and Kim, Sang-Woo and Deng, Junjun and Gustafsson, {\"O}rjan}
}
@article {2738,
	title = {Remobilization of old permafrost carbon to Chukchi Sea sediments during the end of the last deglaciation},
	journal = {Global Biogeochemical Cycles},
	year = {2018},
	month = {Jan-12-2019},
	abstract = {Climate warming is expected to destabilize permafrost carbon (PF-C) by thaw-erosion and deepening of the seasonally thawed active layer and thereby promote PF-C mineralization to CO2 and CH4. A similar PF-C remobilization might have contributed to the increase in atmospheric CO2 during deglacial warming after the last glacial maximum. Using carbon isotopes and terrestrial biomarkers (Δ14C, δ13C, and lignin phenols), this study quantifies deposition of terrestrial carbon originating from permafrost in sediments from the Chukchi Sea (core SWERUS-L2-4-PC1). The sediment core reconstructs remobilization of permafrost carbon during the late Aller{\o}d warm period starting at 13,000 cal years before present (BP), the Younger Dryas, and the early Holocene warming until 11,000 cal years BP and compares this period with the late Holocene, from 3,650 years BP until present. Dual-carbon-isotope-based source apportionment demonstrates that Ice Complex Deposit{\textemdash}ice- and carbon-rich permafrost from the late Pleistocene (also referred to as Yedoma){\textemdash}was the dominant source of organic carbon (66 {\textpm} 8\%; mean {\textpm} standard deviation) to sediments during the end of the deglaciation, with fluxes more than twice as high (8.0 {\textpm} 4.6 g{\textperiodcentered}m-2{\textperiodcentered}year-1) as in the late Holocene (3.1 {\textpm} 1.0 g{\textperiodcentered}m-2{\textperiodcentered}year-1). These results are consistent with late deglacial PF-C remobilization observed in a Laptev Sea record, yet in contrast with PF-C sources, which at that location were dominated by active layer material from the Lena River watershed. Release of dormant PF-C from erosion of coastal permafrost during the end of the last deglaciation indicates vulnerability of Ice Complex Deposit in response to future warming and sea level changes.},
	keywords = {carbon isotope, climate change feedback, coastal erosion, Deglaciation, past carbon cycling, permafrost},
	issn = {0886-6236},
	doi = {10.1029/2018GB005969},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2018GB005969https://onlinelibrary.wiley.com/doi/pdf/10.1029/2018GB005969https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1029\%2F2018GB005969https://onlinelibrary.wiley.com/doi/pdf/10.1029/2018GB005969},
	author = {Martens, Jannik and Wild, Birgit and Pearce, Christof and Tesi, Tommaso and Andersson, August and Broder, Lisa and O{\textquoteright}Regan, Matt and Jakobsson, Martin and Sk{\"o}ld, Martin and Gemery, Laura and Cronin, Thomas M. and Semiletov, Igor and Dudarev, Oleg V. and Gustafsson, {\"O}rjan}
}
@article {2799,
	title = {Residential Coal Combustion as a Source of Levoglucosan in ChinaResidential Coal Combustion as a Source of Levoglucosan in China},
	journal = {Environmental Science \& Technology},
	volume = {52},
	year = {2018},
	month = {Jun-02-2018},
	pages = {1665 - 1674},
	abstract = {Levoglucosan (LG) has been widely identified as a specific marker for biomass burning (BB) sources and frequently utilized in estimating the BB contribution to atmospheric fine particles all over the world. However, this study provides direct evidence to show that coal combustion (CC) is also a source of LG, especially in the wintertime in Northern China, based on both source testing and ambient measurement. Our results show that low-temperature residential CC could emit LG with emission factors (EF) ranging from 0.3 to 15.9 mg kg{\textendash}1. Ratios of LG to its isomers, mannosan and galactosan, differ between CC and BB emissions, and the wintertime ratios in Beijing ambient PM2.5 and source-specific tracers including carbon isotopic signatures all indicated a significant contribution from CC to ambient levoglucosan in winter in Beijing. The results suggest that LG cannot be used as a distinct source marker for biomass burning in special cases such as some cities in the northern China, where coal is still widely used in the residential and industrial sectors. Biomass burning sources could be overestimated, although such an over-estimation could vary spatially and temporally.},
	issn = {0013-936X},
	doi = {10.1021/acs.est.7b05858},
	url = {https://pubs.acs.org/doi/10.1021/acs.est.7b05858},
	author = {Yan, Caiqing and Zheng, Mei and Sullivan, Amy P. and Shen, Guofeng and Chen, Yingjun and Wang, Shuxiao and Zhao, Bin and Cai, Siyi and Desyaterik, Yury and Li, Xiaoying and Zhou, Tian and Gustafsson, {\"O}rjan and Collett, Jeffrey L.}
}
@article {2882,
	title = {Carbon geochemistry of plankton-dominated samples in the Laptev and East Siberian shelves: contrasts in suspended particle composition},
	journal = {Ocean Science},
	volume = {13},
	year = {2017},
	month = {Jan-01-2017},
	pages = {735 - 748},
	abstract = {Recent Arctic studies suggest that sea ice decline and permafrost thawing will affect phytoplankton dynamics and stimulate heterotrophic communities. However, in what way the plankton composition will change as the warming proceeds remains elusive. Here we investigate the chemical signature of the plankton-dominated fraction of particulate organic matter (POM) collected along the Siberian Shelf. POM (> 10 {\textmu}m) samples were analysed using molecular biomarkers (CuO oxidation and IP25) and dual-carbon isotopes (δ13C and Δ14C). In addition, surface water chemical properties were integrated with the POM (> 10 {\textmu}m) dataset to understand the link between plankton composition and environmental conditions.

δ13C and Δ14C exhibited a large variability in the POM (> 10 {\textmu}m) distribution while the content of terrestrial biomarkers in the POM was negligible. In the Laptev Sea (LS), δ13C and Δ14C of POM (> 10 {\textmu}m) suggested a heterotrophic environment in which dissolved organic carbon (DOC) from the Lena River was the primary source of metabolisable carbon. Within the Lena plume, terrestrial DOC probably became part of the food web via bacteria uptake and subsequently transferred to relatively other heterotrophic communities (e.g. dinoflagellates). Moving eastwards toward the sea-ice-dominated East Siberian Sea (ESS), the system became progressively more autotrophic. Comparison between δ13C of POM (> 10 {\textmu}m) samples and CO2aq concentrations revealed that the carbon isotope fractionation increased moving towards the easternmost and most productive stations.

In a warming scenario characterised by enhanced terrestrial DOC release (thawing permafrost) and progressive sea ice decline, heterotrophic conditions might persist in the LS while the nutrient-rich Pacific inflow will likely stimulate greater primary productivity in the ESS. The contrasting trophic conditions will result in a sharp gradient in δ13C between the LS and ESS, similar to what is documented in our semi-synoptic study.},
	doi = {10.5194/os-13-735-2017},
	url = {https://os.copernicus.org/articles/13/735/2017/},
	author = {Tesi, Tommaso and Geibel, Marc C. and Pearce, Christof and Panova, Elena and Vonk, Jorien E. and Karlsson, Emma and Salvado, Joan A. and Krus{\r a}, Martin and Broder, Lisa and Humborg, Christoph and Semiletov, Igor and Gustafsson, {\"O}rjan}
}
@article {2465,
	title = {Carbon isotope-constrained seasonality of carbonaceous aerosol sources from an urban location (Kanpur) in the Indo-Gangetic Plain},
	journal = {Journal of Geophysical Research: Atmospheres},
	volume = {122},
	year = {2017},
	month = {Apr-05-2018},
	pages = {4903 - 4923},
	abstract = {The Indo-Gangetic Plain (IGP) in northern India, Pakistan and Bangladesh is a major source of carbonaceous aerosols in South Asia. However, poorly constrained seasonality of their sources over the IGP leads to large uncertainty in climate and health effects. Here, we present a first dataset for year-round radiocarbon (Δ14C) and stable carbon (δ13C) based source apportionment of total carbon (TC) in ambient PM10 (n = 17) collected from an urban site (Kanpur: 26.5 {\textdegree}N, 80.3 {\textdegree}E) in the IGP during January 2007-January 2008. The year-round 14C-based fraction biomass (fbio-TC) estimate at Kanpur averages ~77 {\textpm} 7\%, emphasize an impact of biomass burning emissions (BBEs). The highest fbio-TC(\%) is observed in fall season (October-November: 85 {\textpm} 6\%) followed by winter (December-February: 80 {\textpm} 4\%) and spring (March-May: 75 {\textpm} 8\%), while lowest values found in summer (June-September: 69 {\textpm} 2\%). Since biomass/coal combustion and vehicular emissions mostly contribute to carbonaceous aerosols over the IGP, we predict δ13CTC (δ13Cpred) over Kanpur using known δ13C source signatures and the measured Δ14C value of each sample. The seasonal variability of δ13Cobs - δ13Cpred versus Δ14CTC together with air mass back trajectories and MODIS fire count data reveal that carbonaceous aerosols in winter/fall are significantly influenced by atmospheric aging (downwind transport of crop-residue burning/wood combustion emissions in the northern IGP), while local sources (wheat residue combustion/vehicular emissions) dominate in spring/summer. Given the large temporal and seasonal variability in sources and emission strength of TC over the IGP, 14C-based constraints are, thus, crucial for reducing their uncertainties in carbonaceous aerosol budgets in climate models. 

Carbon isotope-constrained seasonality of carbonaceous aerosol sources from an urban location (Kanpur) in the Indo-Gangetic Plain: 14Capportionment of carbonaceous aerosol. Available from: https://www.researchgate.net/publication/315970418_Carbon_isotope-constrained_seasonality_of_carbonaceous_aerosol_sources_from_an_urban_location_Kanpur_in_the_Indo-Gangetic_Plain_14Capportionment_of_carbonaceous_aerosol [accessed Jun 2, 2017].},
	doi = {10.1002/2016JD025634},
	url = {http://doi.wiley.com/10.1002/jgrd.v122.9http://doi.wiley.com/10.1002/2016JD025634http://onlinelibrary.wiley.com/wol1/doi/10.1002/2016JD025634/fullpdfhttps://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002\%2F2016JD025634},
	author = {Bikkina, Srinivas and Andersson, August and Ram, Kirpa and Sarin, M. M. and Sheesley, Rebecca J. and Kirillova, Elena N. and Rengarajan, R. and Sudheer, A. K. and Gustafsson, {\"O}rjan}
}
@article {2778,
	title = {Divergent Evolution of Carbonaceous Aerosols during Dispersal of East Asian Haze},
	journal = {Scientific Reports},
	volume = {7},
	year = {2017},
	month = {Jan-12-2017},
	abstract = {Wintertime East Asia is plagued by severe haze episodes, characterized by large contributions of carbonaceous aerosols. However, the sources and atmospheric transformations of these major components are poorly constrained, hindering development of efficient mitigation strategies and detailed modelling of effects. Here we present dual carbon isotope (δ13C and Δ14C) signatures for black carbon (BC), organic carbon (OC) and water-soluble organic carbon (WSOC) aerosols collected in urban (Beijing and BC for Shanghai) and regional receptors (e.g., Korea Climate Observatory at Gosan) during January 2014. Fossil sources (>50\%) dominate BC at all sites with most stemming from coal combustion, except for Shanghai, where liquid fossil source is largest. During source-to-receptor transport, the δ13C fingerprint becomes enriched for WSOC but depleted for water-insoluble OC (WIOC). This reveals that the atmospheric processing of these two major pools are fundamentally different. The photochemical aging (e.g., photodissociation, photooxidation) during formation and transport can release CO2/CO or short-chain VOCs with lighter carbon, whereas the remaining WSOC becomes increasingly enriched in δ13C. On the other hand, several processes, e.g., secondary formation, rearrangement reaction in the particle phase, and photooxidation can influence WIOC. Taken together, this study highlights high fossil contributions for all carbonaceous aerosol sub-compartments in East Asia, and suggests different transformation pathways for different classes of carbonaceous aerosols.},
	doi = {10.1038/s41598-017-10766-4},
	url = {http://www.nature.com/articles/s41598-017-10766-4},
	author = {Fang, Wenzheng and Andersson, August and Zheng, Mei and Lee, Meehye and Holmstrand, Henry and Kim, Sang-Woo and Du, Ke and Gustafsson, {\"O}rjan}
}
@article {2467,
	title = {Siberian Arctic black carbon sources constrained by model and observation},
	journal = {Proceedings of the National Academy of Sciences},
	volume = {114},
	year = {2017},
	month = {Feb-02-2018},
	pages = {E1054 - E1061},
	abstract = {Black carbon (BC) in haze and deposited on snow and ice can have strong effects on the radiative balance of the Arctic. There is a geographic bias in Arctic BC studies toward the Atlantic sector, with lack of observational constraints for the extensive Russian Siberian Arctic, spanning nearly half of the circum-Arctic. Here, 2 y of observations at Tiksi (East Siberian Arctic) establish a strong seasonality in both BC concentrations (8 ng.m-3 to 302 ng.m-3) and dual-isotope{\textendash}constrained sources (19 to 73\% contribution from biomass burning). Comparisons between observations and a dispersion model, coupled to an anthropogenic emissions inventory and a fire emissions inventory, give mixed results. In the European Arctic, this model has proven to simulate BC concentrations and source contributions well. However, the model is less successful in reproducing BC concentrations and sources for the Russian Arctic. Using a Bayesian approach, we show that, in contrast to earlier studies, contributions from gas flaring (6\%), power plants (9\%), and open fires (12\%) are relatively small, with the major sources instead being domestic (35\%) and transport (38\%). The observation-based evaluation of reported emissions identifies errors in spatial allocation of BC sources in the inventory and highlights the importance of improving emission distribution and source attribution, to develop reliable mitigation strategies for efficient reduction of BC impact on the Russian Arctic, one of the fastest-warming regions on Earth.},
	keywords = {Arctic haze, atmospheric transport modeling, carbon isotopes, Climate change, emission inventory},
	issn = {0027-8424},
	doi = {10.1073/pnas.1613401114},
	url = {http://www.pnas.org/lookup/doi/10.1073/pnas.1613401114https://syndication.highwire.org/content/doi/10.1073/pnas.1613401114http://www.pnas.org/syndication/doi/10.1073/pnas.1613401114},
	author = {Winiger, Patrik and Andersson, August and Eckhardt, Sabine and Stohl, Andreas and Semiletov, Igor P. and Dudarev, Oleg V. and Charkin, Alexander and Shakhova, Natalia and Klimont, Zbigniew and Heyes, Chris and Gustafsson, {\"O}rjan}
}
@article {2466,
	title = {Dual carbon isotope characterization of total organic carbon in wintertime carbonaceous aerosols from northern India},
	journal = {Journal of Geophysical Research: Atmospheres},
	volume = {121},
	year = {2016},
	month = {Apr-05-2017},
	pages = {4797 - 4809},
	abstract = {Large-scale emissions of carbonaceous aerosols (CA) from South Asia impact both regional climate and air quality, yet their sources are not well constrained. Here we use source-diagnostic stable and radiocarbon isotopes (δ13C and Δ14C) to characterize CA sources at a semiurban site (Hisar: 29.2{\textdegree}N, 75.2{\textdegree}E) in the NW Indo-Gangetic Plain (IGP) and a remote high-altitude location in the Himalayan foothills (Manora Peak: 29.4{\textdegree}N, 79.5{\textdegree}E, 1950 m above sea level) in northern India during winter. The Δ14C of total aerosol organic carbon (TOC) varied from -178{\textperthousand} to -63{\textperthousand} at Hisar and from -198{\textperthousand} to -1{\textperthousand} at Manora Peak. The absence of significant differences in the 14C-based fraction biomass of TOC between Hisar (0.81 {\textpm} 0.03) and Manora Peak (0.82 {\textpm} 0.07) reveals that biomass burning/biogenic emissions (BBEs) are the dominant sources of CA at both sites. Combining this information with δ13C, other chemical tracers (K+/OC and SO42-/EC) and air mass back trajectory analyses indicate similar source regions in the IGP (e.g., Punjab and Haryana). These results highlight that CA from BBEs in the IGP are not only confined to the atmospheric boundary layer but also extend to higher elevations of the troposphere, where the synoptic-scale circulations could substantially influence their abundances both to the Himalayas and over the downwind oceanic regions such as the Indian Ocean. Given the vast emissions of CA from postharvest crop residue combustion practices in the IGP during early Northeast Monsoon, this information is important for both improved process and model understanding of climate and health effects, as well as in guiding policy decision aiming at reducing emissions.},
	doi = {10.1002/2016JD024880},
	url = {http://doi.wiley.com/10.1002/2016JD024880https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002\%2F2016JD024880},
	author = {Bikkina, Srinivas and Andersson, August and Sarin, M. M. and Sheesley, R. J. and Kirillova, E. and Rengarajan, R. and Sudheer, A. K. and Ram, K. and Gustafsson, {\"O}rjan}
}
@article {2469,
	title = {Isotope-Based Source Apportionment of EC Aerosol Particles during Winter High-Pollution Events at the Zeppelin Observatory, Svalbard},
	journal = {Environmental Science \& Technology},
	volume = {49},
	year = {2015},
	month = {Jun-10-2015},
	pages = {11959 - 11966},
	abstract = {Black carbon (BC) aerosol particles contribute to climate warming of the Arctic, yet both the sources and the source-related effects are currently poorly constrained. Bottom-up emission inventory (EI) approaches are challenged for BC in general and the Arctic in particular. For example, estimates from three different EI models on the fractional contribution to BC from biomass burning (north of 60{\textdegree} N) vary between 11\% and 68\%, each acknowledging large uncertainties. Here we present the first dual-carbon isotope-based (Δ14C and δ13C) source apportionment of elemental carbon (EC), the mass-based correspondent to optically defined BC, in the Arctic atmosphere. It targeted 14 high-loading and high-pollution events during January through March of 2009 at the Zeppelin Observatory (79{\textdegree} N; Svalbard, Norway), with these representing one-third of the total sampling period that was yet responsible for three-quarters of the total EC loading. The top-down source-diagnostic 14C fingerprint constrained that 52 {\textpm} 15\% (n = 12) of the EC stemmed from biomass burning. Including also two samples with 95\% and 98\% biomass contribution yield 57 {\textpm} 21\% of EC from biomass burning. Significant variability in the stable carbon isotope signature indicated temporally shifting emissions between different fossil sources, likely including liquid fossil and gas flaring. Improved source constraints of Arctic BC both aids better understanding of effects and guides policy actions to mitigate emissions.},
	issn = {0013-936X},
	doi = {10.1021/acs.est.5b02644},
	url = {http://pubs.acs.org/doi/10.1021/acs.est.5b02644http://pubs.acs.org/doi/pdf/10.1021/acs.est.5b02644},
	author = {Winiger, Patrik and Andersson, August and Yttri, Karl E. and Tunved, Peter and Gustafsson, {\"O}rjan}
}
@article { ISI:000368907500001,
	title = {Multimolecular tracers of terrestrial carbon transfer across the pan-Arctic: C-14 characteristics of sedimentary carbon components and their environmental controls},
	journal = {GLOBAL BIOGEOCHEMICAL CYCLES},
	volume = {29},
	number = {{11}},
	year = {2015},
	month = {NOV},
	pages = {1855-1873},
	type = {Article},
	abstract = {Distinguishing the sources, ages, and fate of various terrestrial organic carbon (OC) pools mobilized from heterogeneous Arctic landscapes is key to assessing climatic impacts on the fluvial release of carbon from permafrost. Through molecular C-14 measurements, including novel analyses of suberin- and/or cutin-derived diacids (DAs) and hydroxy fatty acids (FAs), we compared the radiocarbon characteristics of a comprehensive suite of terrestrial markers (including plant wax lipids, cutin, suberin, lignin, and hydroxy phenols) in the sedimentary particles from nine major arctic and subarctic rivers in order to establish a benchmark assessment of the mobilization patterns of terrestrial OC pools across the pan-Arctic. Terrestrial lipids, including suberin-derived longer-chain DAs (C-24,C-26,C-28), plant wax FAs (C(24,26,2)8), and n-alkanes (C-27,C-29,C-31), incorporated significant inputs of aged carbon, presumably from deeper soil horizons. Mobilization and translocation of these {\textquoteleft}{\textquoteleft}old{{\textquoteright}{\textquoteright}} terrestrial carbon components was dependent on nonlinear processes associated with permafrost distributions. By contrast, shorter-chain (C-16,C-18) DAs and lignin phenols (as well as hydroxy phenols in rivers outside eastern Eurasian Arctic) were much more enriched in C-14, suggesting incorporation of relatively young carbon supplied by runoff processes from recent vegetation debris and surface layers. Furthermore, the radiocarbon content of terrestrial markers is heavily influenced by specific OC sources and degradation status. Overall, multitracer molecular C-14 analysis sheds new light on the mobilization of terrestrial OC from arctic watersheds. Our findings of distinct ages for various terrestrial carbon components may aid in elucidating fate of different terrestrial OC pools in the face of increasing arctic permafrost thaw.},
	issn = {0886-6236},
	doi = {10.1002/2015GB005204},
	author = {Feng, Xiaojuan and Gustafsson, {\"O}rjan and Holmes, R. Max and Vonk, Jorien E. and van Dongen, Bart E. and Semiletov, Igor P. and Dudarev, Oleg V. and Yunker, Mark B. and Macdonald, Robie W. and Wacker, Lukas and Montlu{\c c}on, Daniel B. and Eglinton, Timothy I.}
}
@article { ISI:000348452800012,
	title = {Preferential burial of permafrost-derived organic carbon in Siberian-Arctic shelf waters},
	journal = {JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS},
	volume = {119},
	number = {{12}},
	year = {2014},
	month = {DEC},
	pages = {8410-8421},
	type = {Article},
	abstract = {The rapidly changing East Siberian Arctic Shelf (ESAS) receives large amounts of terrestrial organic carbon (OC) from coastal erosion and Russian-Arctic rivers. Climate warming increases thawing of coastal Ice Complex Deposits (ICD) and can change both the amount of released OC, as well as its propensity to be converted to greenhouse gases (fueling further global warming) or to be buried in coastal sediments. This study aimed to unravel the susceptibility to degradation, and transport and dispersal patterns of OC delivered to the ESAS. Bulk and molecular radiocarbon analyses on surface particulate matter (PM), sinking PM and underlying surface sediments illustrate the active release of old OC from coastal permafrost. Molecular tracers for recalcitrant soil OC showed ages of 3.4-13 C-14-ky in surface PM and 5.5-18 C-14-ky in surface sediments. The age difference of these markers between surface PM and surface sediments is larger (i) in regions with low OC accumulation rates, suggesting a weaker exchange between water column and sediments, and (ii) with increasing distance from the Lena River, suggesting preferential settling of fluvially derived old OC nearshore. A dual-carbon end-member mixing model showed that (i) contemporary terrestrial OC is dispersed mainly by horizontal transport while being subject to active degradation, (ii) marine OC is most affected by vertical transport and also actively degraded in the water column, and (iii) OC from ICD settles rapidly and dominates surface sediments. Preferential burial of ICD-OC released into ESAS coastal waters might therefore lower the suggested carbon cycle climate feedback from thawing ICD permafrost.},
	keywords = {biomarkers, carbon, permafrost, radiocarbon},
	issn = {2169-9275},
	doi = {10.1002/2014JC010261},
	author = {Vonk, Jorien E. and Semiletov, Igor P. and Dudarev, Oleg V. and Eglinton, Timothy I. and Andersson, August and Shakhova, Natalia and Charkin, Alexander and Heim, Birgit and Gustafsson, {\"O}rjan}
}
@article {226,
	title = {14C-Based source assessment of soot aerosols in Stockholm and the Swedish EMEP-Aspvreten regional background site},
	journal = {Atmospheric Environment},
	volume = {45},
	year = {2011},
	note = {id: 2148},
	pages = {215-222},
	abstract = {Combustion-derived soot or black carbon (BC) in the atmosphere has a strong influence on both climate and human health. In order to propose effective mitigation strategies for BC emissions it is of importance to investigate geographical distributions and seasonal variations of BC emission sources. Here, a radiocarbon methodology is used to distinguish between fossil fuel and biomass burning sources of soot carbon (SC). SC is isolated for subsequent off-line 14C quantification with the chemothermal oxidation method at 375 {\textdegree}C (CTO-375 method), which reflects a recalcitrant portion of the BC continuum known to minimize inadvertent inclusion of any non-pyrogenic organic matter. Monitored wind directions largely excluded impact from the Stockholm metropolitan region at the EMEP-Aspvreten rural station 70 km to the south-west. Nevertheless, the Stockholm city and the rural stations yielded similar relative source contributions with fraction biomass (fbiomass) for fall and winter periods in the range of one-third to half. Large temporal variations in 14C-based source apportionment was noted for both the 6 week fall and the 4 month winter observations. The fbiomass appeared to be related to the SC concentration suggesting that periods of elevated BC levels may be caused by increased wood fuel combustion. These results for the largest metropolitan area in Scandinavia combine with other recent 14C-based studies of combustion-derived aerosol fractions to suggest that biofuel combustion is contributing a large portion of the BC load to the northern European atmosphere.},
	issn = {1352-2310},
	doi = {10.1016/j.atmosenv.2010.09.015},
	url = {http://www.sciencedirect.com/science/article/pii/S1352231010007697},
	author = {Andersson, August and Sheesley, Rebecca J. and Krus{\r a}, Martin and Johansson, Christer and Gustafsson, {\"O}rjan}
}
@conference {958,
	title = {Year-round probing of soot carbon and secondary organic carbon contributions and sources to the South Asian Atmospheric Brown Cloud using radiocarbon (14C) measurements},
	booktitle = {EGU General Assembly 2010, held 2-7 May, 2010 in Vienna, Austria},
	volume = {12},
	year = {2010},
	note = {id: 870Y},
	month = {05/2010},
	abstract = {South Asia is one region of vital importance for assessing human impact on radiative forcing by atmospheric aerosols. Previous research in the region has indicated that black carbon is a significant component of the regional aerosol load. In contrast, there is more ambiguous information regarding the contribution of secondary organic aerosols (SOA) to the total carbonaceous (TC) aerosol composition. Here we primarily address the SOA component of the South Asian Atmospheric Brown Cloud (ABC) by a combination of measurements of SOA concentrations and the 14C signature of TC. Atmospheric particulate matter was collected during fourteen-month continuous sampling campaigns Jan 2008 - March 2009 at both the Maldives Climate Observatory at Hannimaadho (MCO-H) and at the Sinhagad hilltop sampling site of the Indian Institute of Tropical Meteorology (SIN) in central-western India. The radiocarbon method is an ideal approach to identify fossil sources (14C "dead") compared to biogenic and biomass combustion products (with a contemporary 14C signal). The radiocarbon source apportionment of TC revealed very similar contribution from biogenic/biomass combustion (60-70\%) for Indian SIN site and the MCOH receptor regions for much of the year. However, during the summer monsoon season biomass contribution to TC at the Indian Ocean site increases to 70-80\%, while it decreases to 40-50\% at the Indian site. Source apportionment of a soot carbon (SC) isolate (CTO-375 method; a tracer of black carbon) shows a similar trend. According to preliminary data in summer biomass contribution is higher at the MCOH receptor site (70\%) compared to the SIN background site (45\%). These unique year-round 14C data will be interpreted in view of the SOA concentration and the varying origin of the air masses.},
	author = {Kirillova, Elena and Sheesley, Rebecca J. and Andersson, August and Krus{\r a}, Martin and Safai, P. D. and Budhavant, Krishnakant and Rao, P. S. P. and Praveen, P. S. and Gustafsson, {\"O}rjan}
}
@article {905,
	title = {Source apportionment of atmospheric PAHs in the western Balkans by natural abundance radiocarbon analysis},
	journal = {Environmental Science and Technology},
	volume = {41},
	year = {2007},
	note = {id: 519},
	pages = {3850-3855},
	doi = {10.1021/es0628957},
	author = {Zencak, Zdenek and Klanova, Jana and Holoubek, Ivan and Gustafsson, {\"O}rjan}
}
